Oral history is the collection and study of historical information from people, families, important events, or everyday life using audiotapes, videotapes, or transcriptions of planned interviews. These interviews are conducted with people who participated in or observed past events and whose memories and perceptions of these are to be preserved as an aural record for future generations. Oral history strives to obtain information from different perspectives and most of these cannot be found in written sources. Oral history also refers to information gathered in this manner and to a written work (published or unpublished) based on such data, often preserved in archives and large libraries. Knowledge presented by oral history is unique in that it shares the tacit perspective, thoughts, opinions and understanding of the interviewee in its primary form.